Indivdual reproductive decisions: Behavioral mechanisms and adaptive significance

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This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Understanding the processes that produce and maintain genetic variation is a critical goal of modern biology. Of the many behavioral processes that may influence genetic variation, few are as directly influential as reproductive decisions. Choice of a reproductive partner determines which genetic information is transmitted across generations and affects offspring health and reproductive success. Only recently has it been appreciated that individual females may vary considerably in their reproductive decisions and that this variability can be critical in maintaining population genetic variation and diverse male courtship behaviors. This study investigates female reproductive decisions in a lekking passerine bird, the lance-tailed manakin (Chiroxiphia lanceolata). In lek systems, females actively assess and choose from among displaying males, but receive nothing but genes from their chosen partner (there is no paternal care, and males do not control access to food or nesting resources). Genetic paternity analyses have revealed that female lance-tailed manakins frequently change their choice of partners in different breeding seasons, even when previously-favored partners are still available and reproduce successfully with other females. Females assess the same males, but make different reproductive decisions. This project combines field observations of behavior, automated radio-tracking of females, and genetic analyses of paternity and variation to (1) characterize the behavioral mechanisms that generate variation in partner preferences; (2) identify female characteristics associated with this variation (e.g. age, condition, and reproductive experience); and (3) test hypotheses about the benefits of variable reproductive decisions to individual females. This work will provide much-needed empirical evidence to test the idea that variable female reproductive choices influence the process of sexual selection in wild populations. Furthermore, the project will provide training opportunities for graduate and undergraduate students, results useful in university-level teaching, and educational benefits through outreach presentations to the general public in the US and Panama.